Read the following passage and choose the best answer (A, B, C or D) for each question
Although they are safe to use in the short term, coal, gas and oil present a long term threat to the environment. All three types of fossil fuels produce carbon dioxide in far greater quantities than plants can use. The carbon dioxide then accumulates in the atmosphere and may even increase the earth’s “heat load” and lead to global rises in temperature. Furthermore, all three fossil fuels are non-renewable forms of energy.
Geothermal power is unlikely ever to be an energy source of major importance. It is limited and is exploitable in only a few places. Hydro-power offers a much more useful source of energy. It is also renewable but its availability is limited. Dams cannot be built in certain areas. Wind power is a pollution-free source of energy but it cannot be used in many parts of the world where there is insufficient wind. Wave power is non - polluting and doesn’t add to the earth’s heat but it is ineffective where the sea is usually calm.
Solar power is renewable. It neither causes pollution nor adds to the earth’s heat load. Unfortunately, solar power is not distributed equally and it also requires expensive equipment. Finally, nuclear power provides a very efficient and renewable power source. However, not only is there a great danger of leaks or accidents but there is also the problem of the disposal of radioactive waste.
The threat caused by fossil fuels in the long term is _____________.
